[Objective] To study the microstructure of ligamentum fiavum of the early dynamic imbalanced rats.[Methods]The dynamic imbalanced rat mode was established.The samples were taken and studied by electron microscopy at 3、5、15、30、60 days after operation.[Results]A large number of fibroblasts in the ligamentum flavum were found at 3 days after the neck muscles were resected.The fibroblasts had an active metabolism,and around them the collagen fibers were markedly increased at 5 days.The number of fibroblasts was reduced,but the matrices were increased at 15 days.At 30 days,fibroblasts became slender,and fibers looked like waves.At 60 days,the number and appearance of the fibroblasts of the ligamentum fiavum were similar to that of the control group.The fibers were regularly arranged and became larger than that of the colltrol group.[Conclusion]The number of fibroblasts and the collagen fibers in the ligamentum flavum of the dynamic imbanlanced rats has a regular change after operation.